Fetch any public URL and analyze its HTTP security headers: status, server tech, present/missing security headers, 0-100 score and A-F grade. [PAID: $0.015 USDC per call via x402]
| Name | Required | Description | Default |
|---|---|---|---|
| url | Yes | Public http(s) URL to analyze |
Changes observed during successful MCP inspections.
Input schema / additionalPropertiesPrevious value: -trueNew value: +falseInput schema / properties / promptRemoved value: -{
- "description": "Input prompt for this service.",
- "type": "string"
-}Input schema / properties / urlAdded value: +{
+ "description": "Public http(s) URL to analyze",
+ "type": "string"
+}Input schema / requiredPrevious value: -[
- "prompt"
-]New value: +[
+ "url"
+]Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral burden, and it does disclose a genuinely non-obvious trait: the tool is paid ($0.015 USDC per call via x402), which tells the agent a payment/auth step is involved before invocation. It also reveals the returned signal set. It stops short of describing failure modes (non-public URLs, redirects, timeouts) or rate limits.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
One sentence, front-loaded with the core action and followed by the exact set of returned signals, with the pricing bracketed separately at the end. Nothing is redundant and nothing that matters is buried.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
There is no output schema, so the description usefully compensates by enumerating the return fields (status, server tech, header presence, 0-100 score, A-F grade) and the cost. For a one-parameter read-only analyzer this is nearly complete, with only edge-case/error behavior left unstated.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
There is a single parameter with 100% schema description coverage ('Public http(s) URL to analyze'), so the schema already carries the semantics. The description's 'any public URL' adds only marginal reinforcement of the public-reachability constraint, matching the baseline 3 for schema-documented single-param tools.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
States a concrete verb and resource ('Fetch any public URL and analyze its HTTP security headers') and enumerates the outputs (status, server tech, present/missing headers, score, grade), so the agent knows exactly what the tool produces. It does not explicitly differentiate itself from URL-oriented siblings such as liminal-stack-intel or liminal-url-to-text, which keeps it short of a 5.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The only usage constraint is the implied scope of 'public URL'. There is no when-to-use/when-not guidance and no named alternative, even though sibling tools (liminal-stack-intel for server tech, liminal-url-to-text for page content) plausibly overlap. The agent must infer the selection rule.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Add one secure layer between your agents and this server.